The present invention generally relates to accounting systems, and more particularly to an integrated accounting system applicable to a network structure which includes a telephone network and a packet network.
Recently, due to the development of public telephone sets, card type public telephone sets are becoming popular in addition to conventional coin type public telephone sets. According to the card type public telephone set, a card is recorded with a predetermined number of units and a number of units corresponding to a charge on a call is subtracted from the card instead of collecting inserted coins. In other words, the card type public telephone set also employs an advance payment system and the number of units corresponding to the charge on the call is subtracted from the card responsive to an account signal received from a telephone exchange. On the other hand, there is an increasing demand to connect a data terminal to the card type public telephone set so as to make a data communication. In addition, with the extension of the telephone exchange network, there is a demand to make a data communication with a packet mode terminal of a packet exchange network.
FIG. 1 generally shows an example of a conventional network structure which includes a telephone network and a packet network. The network structure shown includes a telephone network TN, a packet network PN, a telephone exchange 1 within the telephone network TN, a packet exchange 2 within the packet network PN, a gate way 3, an advance payment type terminal 4, a packet mode terminal 5, and a data terminal 6.
The telephone exchange 1 has an accounting function of charging a fee for a telephone call depending on a conversation time (that is, duration) and distance of the telephone call. With respect to the terminal 4 such as a card type public telephone set, the telephone exchange 1 also has a function of sending a control signal for counting up an accounting number for every accounting unit which is dependent on a duration and distance of the telephone call within the telephone network TN. The terminal 4 has a function of subtracting the fee of the telephone call from the card or collecting coins amounting to the fee of the telephone call every time the control signal is received.
On the other hand, the packet exchange 2 has a function of charging a fee for a data communication depending on an information quantity of the data communication within the packet network PN. The packet exchange 2 also has a function of sending a control signal for accumulating the accounting information when the call is disconnected. The gate way 3 has a function of transmitting and receiving control signals between the telephone exchange 1 and the packet exchange 2, and sends to the telephone exchange 1 a control signal dependent on the accounting information from the packet exchange 2.
In the above described network structure, the terminal 4 which is connected to the telephone network TN calls out for the packet mode terminal 5 which is connected to the packet network PN, for example, so as to make a communication via the gate way 3 and the packet network PN. A conventional method of accounting employs an independent accounting system in which the accounting related to the telephone network TN and the accounting related to the packet network PN are made independently. In other words, the accounting related to the telephone network TN is made in the telephone exchange 1 while the accounting related to the packet network PN is made in the packet exchange 2. According to this independent accounting system, only the accounting related to the telephone network TN can be collected from the advance payment made at the terminal 4. The accounting related to the packet network PN is saved in the packet exchange 2 and the user is later charged based thereon. Hence, the user who wishes to make access to the packet network PN from the terminal 4 must be a registered user so that the accounting related to the packet network PN may be later charged, and the user must identify himself by entering his user identification number, for example. As a result, there is a problem in that the access to the packet network PN from the terminal 4 can only be made by a registered user who is authorized to make the access. In addition, there is a problem in that the charge on the communication is made independently for the telephone network TN and the packet network PN at different times, thereby making the network structure not very user-friendly.
FIG. 2 is a time chart for explaining the conventional accounting method employing the independent accounting system.
On the other hand, there is a conventional accounting method employing an integrated accounting system. According to the integrated accounting system, the accounting related to the telephone network TN is made in the telephone exchange 1 while the accounting related to the packet network PN is made in the packet exchange 2, and the accounting related to the packet network PN is added to the accounting related to the telephone network TN in the gate way 3 or the telephone exchange 1. The sum of the accountings related to the telephone network TN and the packet network PN is collected from the payment made at the terminal 4. However, the accounting information related to the packet network PN is obtained from the packet exchange 2 only after the call is disconnected, as is the case of the independent accounting system described above, and it is impossible to determine during the communication whether or not an advance payment should be collected in respect of the accounting related to the packet network PN. As a result, there is a problem in that the integrated accounting cannot be made in real-time. Since the coin type and card type public telephone sets are designed to collect an advance payment for each call, the conventional integrated accounting system which does not collect the charge for the call in real-time is not applicable to these public telephone sets. If the conventional integrated accounting system were to be applied to the public telephone set, the access to the packet network PN from the terminal 4 must be restricted to a registered user so that the collection of the charge for the communication using the packet network PN is guaranteed.
FIG. 3 is a time chart for explaining the conventional accounting method employing the integrated accounting system.